Automatic firearm.



I. N. LEWIS.

AUTOMATIC FIREARM.

APPLICATION FILED APR. I6, 1912.

SCIQC JI( Lewis l. N. LEWIS.

AUTOMATIC FIREARM.

APPLICATIoN flu-:D APR.1e. 1912.

Patented June 15, 1915.

2 SHEETS-SHEET 2.

[NVE/WOA [5 aac JM Y[Le wis Unrrp sfra'rns PATENT carica.

ISAAC N. LEWIS, OF NEW YORK, N. Y., ASSIGNOR TO THE AUTOMATIC ARMSCOMPANY, OF BUFFALO, NEW YORK, A CORPORATION OF NEW YORK.

AUTOMATIC FIREARM.

Specification of Letters Patent.

Patented June 15, 1915.

T0 all whom t may concern:

Be it known that I, ISAAC N. Lewis, a citizen of the United States, andresident of New York city, in the county of New York and State of NewYork, have invented certain new and useful Improvements in AutomaticFirearms, of'which the following is a speciication.

This invention relates to firearms and particularly to automatic,gas-operated rearms wherein gases of one discharge store after set forthand claimed.

In the drawings which forrn a part of this specieation, Figure 1represents, in side elevation, a gun in which the features of thisinvention are embodied; Fig. 2 is an enlarged elevation of a portion ofthe gun; Fig. 3 is a transverse section onthe line 3-3 Fig. 2; Fig. 4 isa fragmentary transverse section in the plane indicated' bv the line 4-4Fig. 2; Fig. 5 is a longitudinal, axial, vertical section through thereceiver and gas cylinder; Fig. 6 is a vertical, longitudinal section,full size, through the spring drum and casing and a portion of theslide, sear and trigger; Fig. 7 is a transverse, vertical section online7 7 Fig. 6: Fig. 8 is a transverse section on line 8 8 Fig. 6; Fig. 9 isa sectional View. similar to that in Fig. 6, showing a modification inthe connection between the spring and the piston rod; Fig. 10 is a planof the spring casing and a portion of the slide carrying the grip; Fig.`1l is a transverse section on the line 11-11 Fig. 9; and Fig. 12. is anillustration of the form of gear teeth found necessary for the perfectoperation of the mechanism illustrated in Fig. 5.

The gun shown in the drawings is an aircooled gun and is provided withrotary magazine cartridge feed and is intended to be supported upon atripod when in use.

The present invention, however, is in no sense limited to associationwith these specific features. It is intended for use in any gun whereina portion of the gases of discharge is diverted and used for effectingautomatic firing.

In Fig. 1 the gun barrel and gas cylinder are Within the cooling jacket20. The rotary cartridge magazine is represented at 21, the upper end ofthe tripod support at Q2, the stock at 23, the pistol grip at 24, andthe trigger at 25. In the sectional view of Fig. 5 and in the details ofthe other iigures the special features of the invention appear.

ln gas-operated guns heretofore designed the 'inainspring-the spring inwhich one discharge stores power for the next has usually been locatedin the gas cylinder around the rod of the gas-driven piston. As such gascylinder parallels the gun barrei for the greater portion of the lengthot' the barrel the spring is directly in the heated zone and quicklydeteriorates from the effect of the heat. The present invention replacesthat sort of spring by a small convolute spring located to the rear ofthe gun barrel entirely out of the heated zone. The casing 26 containsthe spring in question. The spring itself is seen at 27 in Figs. 6, 7and 9. lt is preferably so formed as to give practically a constant pullthroughout each action thereof. This is best accomplished by graduallyreducing its cross-sectional area toward the smallest convolution,- asindicated in Fig. 7 preferably bv gradually narrowing the spring whilemaintaining the same thickness.

Fig. 5 illustrates the way in which the spring has been applied inactual use. The casing 26 containing it is removably attached to thelower side of the receiver, to which also the grip 24 is removablyattached. lVithin the receiver, as usual, are the piston rod 28 and thebreech bolt 29 located in their respective cylinders. the breech boltbeing reciprocated, locked ,and unlocked automatically by the iring-pnpost 30, carried by the piston rod and pro- 'iccting into the interiorof the breech bolt, as well understood in this art.

By'reference to Figs. 6 and 7, it will be seen that the spring 27 hasits inner end attached to a hub 31 on the ends of which the spring drumis journaled. This drum conspring is preferably riveted to thisthickened portion of .said inner cup. After the drum is inserted in thecasing the squared. pin 35 is inserted through one side of the casmg anda cap 36 screwed into the opening against the head of the pin, the otherend of the pin being inserted in a squared openingm' the opposite sideof the casing. By rotating the drum in one direction, the spring will beWound upon the hub, then by releasing the drum it Will be rotated in theopposite direction by the spring; Therefore by applying the force4 of aportion of the gases of .eXplosion to the rotation of the drum forWinding up the spring, the .spring in univindmg may be made to drive thefeeding and tiring mechanism ofthe gun. This has been accomplished inthe present instance by forming a rack on the piston rod to mesh withthe teeth formed on the geared section 32 of the spring drum as seen inFig. 5. As heretofore in this class of guns, the gases of dischargeentering the gas cylinder through the port 37 act upon the piston 38 todrive it and the piston rod 28 rearwardly thereby winding up the springwhich on unwinding furnishes alone the full power for operating theiirin g mechanism; driving the piston forward to effect the advance ofthe breech bolt, the insertion of a cartridge, the locking of the breechbolt and the firing of the cartridge, in the manner usual in theautomatic firing of guns of this class. 1f the piston rod is to behalted before firing, the Sear 39 is released by the trigger and entersits notch in the piston rod as seen in Fig. '6. -The sear may then beWithdrawn by the trigger whereupon the spring Will complete is Work.After the first round, the gun Will continue to fire automatically solong as the trigger is pressed. The lirst charge is fed in by handmanipulation of the piston rod as is usual in this class of guns. Themeans for operating the piston rod by hand Will be explained fartheron.'`

This invention provides for the employment of the simplestsort oftrigger and sear mechanism.

slide is fitted to a longitudinal guideway formed in the underside ofthe receiver. This guideway is seen in cross-section at 40 in Fig. 3.The scar 39 is a cupped cylinder spring-seated in a socket in said slide40, as seen in Fig. 6. In the side of the sear is a notch and into thisprojects the end of the bell-crank trigger 25 which is located in arecess in slide 40 and pivoted on pin 41.

They are mounted in the slide' A40 to which the grip 24 is attached.This Through the side of the receiver is formed a slot 42 and in thepiston rod is formed a shorter slot 43. In the slot 43 there is inserteda knob 44, Fig. 3. By this knob the piston may be manually operated, theshank of the knob traversing the slot 42. This knob is preferablyreadily removable from the piston rod. For this reason its shank issplit and the end of each fork is eXteriorly ribbed to spring into arecess at its respective side of the slot 43 on the farther side of thepiston rod. There are similar ribs also formed on the 'shank near theknob and these lie in recesses in the piston rod at either side of theslot 43. They also slide behind the edges of slot 42 which is narrowerthroughout the greater portion of its length than at the rear end Wherethe shank of the knob is to be passed throughvfor insertion in thepiston rod.

To close the slot 42 a, cover 45 is provided Whose ends slide in Waysformed in the Wall of the. receiver just below the ends of said slot 42.-This cover 45 is slid up over the slot When the gun is not in use, tokeep out dirt. It also serves as a safety check, since it is when thegun is cocked that the cover is used. It is therefore notched at 46 tospan the shank of the knob 44. Should the trigger be accidentallypressed when the cover is over the slot, the cover will prevent theadvance of the firing pin. The notch 46 is also preferably undercut atits forward end so that should such accidental pressure of the triggeroccur the shank of the knob will enter said undercut, thereby preventingthe Withdrawal of said cover until the piston rod has been drawn back tococked position. To hold the cover in Withdrawn position or in placeover the slot, a short rib 47 is formed on the back thereof (Fig. 4) torest in a depression in the side of the receiver or over the lower edgeof slot 42 respectively.

As above outlined, the slide 40 is removable by slidingit longitudinallyrearward, the trigger being pressed and the stock having been removedfrom the receiver. The removal of the slide releases the spring casingWhich is pivoted by lug 48 upon a pin 49 traversing a recess in theunderside ofthe receiver. The lug 4S is rounded on its upper surfaceenough to permit the gear casing 'Lo swing down till the teeth on thespring drum are disengaged from the rack on the piston rod.4 As thesprino' 27 should have a little initial tension, means are provided forpreventing its running down When the casing is so swung down or removedaltogether as it may be by pushing out pin 49. A detent 50 is providedin the casing- 26 for engaging the gear teeth on the drum. This ispreferably a spring detent, the integral plate spring 51 serving to holdthe toe in mesh with the teeth. Since this detent must be held out ofengagement With the teeth when the gear is in operative position it isprovided with a heel 52 with which the locking projection 53 on slide 40may engage when all parts are assembled. As projection 53 is inserted inthe recess of the spring casing under the heel 52, the toe is withdrawnfrom the drum gear. The gear of the drum is however then in mesh withthe rack on the piston rod which in turn is held in place by the sear39.

With the spring drum and casing constructed as described, it is an easymatter, should a spring break, to insert a new one. With the new springinserted and the casing in hand, the initial tension is readily given tothe spring by rolling the drum with the thumbs, the detent 50 holdingthe tension so given until the casing is in place on the receiver asabove described.

The adoption of rack and pinion gearing for the joint operation ,of thespring and the piston rod necessitated the development of a special formof gear teeth. Such teeth are illustrated in Fig. 12. In the attempt touse the ordinary involute teeth the upward thrust on the piston rod, dueto the line of pressure incident to such teeth, created so much frictionas to render the mechanism inoperative. The involute teeth weretherefore cut on the inner half of the engaging face (as at 54) inepicycloidal form, the

other three-fourths of each tooth remaining of involute form. Thereforethe engaging or driving faces of the teeth of the rack and pinion arehalf involute and half'epicycloidal. Itiwill be seen that in the actionof rack and* pinion in the present instance, the rack is the drivingelement in one direction while the pinion is the driving element in theother direction. With the teeth cut as above described the line ofpressure upon the rack has been reduced from an angle of 14, that ofinvolute gearing, practically to zero or to parallelism with thedirection of reciprocation of the rack.

The rack and pinion connection between the spring drum and the pistonrod, constructed as above described-, works perfectly yet it is possibleto connect these parts otherwise, therefore the features of thisinvention relating to the adoption of a convolute spring are not to belimited by the use therewith of rack and pinion gearing. Another form ofconnection between the convolute spring and the piston rod isillustrated in Figs. 9, 10 and 11. Therein the casing 26, the spring andthe spring drum, with the exception of the teeth on Aits periphery, andthe manner of mounting the drum in the casing are the same as alreadydescribed.\ Instead of the gear teeth, a metal tape is used forconnecting the spring drum to the piston rod. This tape 55 is connectedat its inner end to the drum 56 vand has a crosspiece 57 secured to itsouter end. When the drum is inserted in the casing this crossv piecerests in the notches y58. Before putting the casing in place on thereceiver, the desired initial tension may be given to the spring bycarrying the crosspiece 57 over into vertical notches 59 at the otherend of the casing. Under the crosspiece when thus located is the end ofa spring arm 60 which arm is pivoted in the casing similarly to thedetent 50. When the casing hasv been put into place', the application ofslide 40 will, by the action of its locking lug, thrust the arm 6Gupward and press up the crosspiece 57 into a notch 61 in the undersideof the piston rod. There the crosspiece stays and las the piston isdriven backward the tape rotates the drum 56 and winds up the spring. Asthe spring unwinds the tape is wound up and the piston returned,performing the functions attending its return as already described. Agroove as indicated at 62 may be formed in the underside of the pistonrod for the tape 55. In removin the casing 26, the crosspiece 57 mustrst be pushed back into notches 59. After slide 40 has been removed,this may be done by reaching in through the aperture 63 vin the end ofthe casing 26.

Many modifications in the general structure and in the details abovedescribed may be made within the spirit of this invention.

The invention claimed isz- 1.In a gas operated gun, the combination ofthe gun barrel, a cylinder paralleling it, a rotary reciprocating breechbolt, a gas-driven piston in said cylinder Whose rod carries the firingpin the post of which operatively engages the breech bolt, and a singlespring mounted at the rear of the gas cylinder and gun barrel andconnected to the piston rod for driving the entire mechanism.

2. In a gas operated gun, the combination of a rotary reciprocatingbreech bolt, a gasdriven piston whose rod carries the firing pin .thepost of which operatively engages the breechA bolt, and a convolutespring operatively connectedto said piston for driving all said partsand located in a readily removable mannerat the rear of the gun barrelfor the purpose set forth.

3. In a gas-operated gun, the combination of a receiver and a gas-drivenpiston, a cylinder for said piston paralleling the gun barrel, a readilydetachable convolute spring mounted on said receiver, an operatingconnection between the piston and spring whereby the spring may beputunder tension, a casing located at the rear of said cylinder andbarrel out of the zone of damaging heat and containing said spring anddetachably connected to the receiver for ready removal, `and feeding andfiring mechanism driven by said spring.

4. In a gas-operated gun, the combination of the receiver and thegas-driven piston, a cylinder for said piston paralleling the gunbarrel, a convolute spring detachthe firing mechanism, and aninterengaging driving connection between said drum and piston saidinterengagement being automatically eii'ected in the act of attachingthe Said casing to the receiver.

6. In a gas-operated gun, the combination with the receiver andgas-operated piston, of a removable spring casing adapted to be lockedto said receiver, a spring-containing drum `within said casingforoperating the firing mechanism, a driving connection between said drumand piston, and automatically acting means for eecting said connectionin the act of locking said casing upon said receiver. l

7. In a gas-operted gun, the combination with the receiver, of agas-driven piston the rod of which reciprocates in said receiver,

fiiring mechanism driven by said rod, a convolute spring for drivingsaid rod, a casing containing said spring and removably attached to thereceiver, means for holding said spring under tension when said casingis removed, and a connection between said spring and the piston rodwhereby the spring may be wound up by the rearward movement of thepiston and in unwinding may operate the firing mechanism.

8. In a gas-operated gun, the combination of the receiver, thegas-operated piston, a convolute spring adapted to be connected to saidpiston for operating the firing mechanism, a casing for holding saidspring removably attached to the receiver, a device holding the springunder tension when the casing is removed from the receiver, and a slidecarrying the grip and trigger mechanism and provided with means forreleasing said tension holding device when-said slide` is put in placeon the receiver.

'9. In a gas-operated gun, the combination with the gas-driven pistonhaving a gear rack upon the piston rod, of a rotary spring drum, apinion driven thereby and adapted to mesh with said rack whereby thepiston may wind up the spring and the spring in unwinding may operatethe firing mecha.-

nism, a removable casing in which said drum is mounted, andA a detent.for engagement.

with the pinion when the casing is removed.

10. In a gaseoperated gun, the combinavtion with the gas-'driven pistonhaving a gear rack upon the piston rod, of a rotary spring drum having apinionV thereon adapted to mesh with said rack, a removable casing inwhich said drum is mounted, a d etent in said casing for engaging theteeth of the pinion, and means for automatically withdrawing said detentfrom said teeth in assembling the parts of the gun.

11. In a gas-operated gun, the combination with a gas-driven pistonhaving a gear rack upon the piston rod, of a rotary spring drum having apinion thereon adapted to mesh with said rack whereby the piston maywind .up the spring andthe spring in unwinding may operate the firingmechanism, the engaging faces of the gear teeth having their outerhalves in involute form and their inner halves in epicycloidal form forthe purpose specified. Y

12. The combination with the spring casing, of a squared pin locatedtransversely in saidcasing, a hub traversed thereby, a @spring drummounted for rotation upon said hub and consisting of an inner cupinserted within an outer one and connected thereto, a spring connectedto said hub and to said inner cup, and driving means provided on theperipheryof said drum.

In a gas-operated gun, the combina- 4 tion with the gas-operated pistonand spring for returning the piston, of the piston rod provided with anotch in its underside, aA

vertically reciprocating Sear for engaging in said notch consisting of acupped cylinder with a notch in its side, a spiral spring seated in thecupped cylinder, and a bell-crank trigger for depressing said sear byits toe engaging thev notch in the side ofsaid cylv inder.

14. In a gas-operated gun, the combination with the gas-driven pistonand spring for -returning the piston, of the piston rod provided withaslot therethrough, and a knob adapted to be removably located in saidslot for manual operation of the piston.

15. In a gas-operated gun, the combina,Jr tion with the gas-drivenpiston, of the receiver provided with a cylinder for the pis- Y ISC N.LEWIS.

